Land Leveler Implement with Bottom-Finned Working Blade

ABSTRACT

A towable implement features a frame, a pull tongue extending longitudinally forward thereof for towed conveyance of the frame over underlying ground, and a working blade lying transversely of the longitudinal direction, said blade being operable to engaged the underlying ground to perform a working operation thereon. The blade is selectively tiltable about a roll axis to adjust an angular position of the blade relative to the underlying ground to enable performance of different working operations thereon. A series of rigid fins are distributed discretely along a width of the blade in a direction transverse to the longitudinal direction, and each rigid fin protrudes downwardly beyond a reference plane occupied by the lower working edge of the blade. In the working state of the blade, at least one of said rigid fins engages said underlying ground in penetrating fashion to perform a rudder-like action helping maintain a straight travel direction of the implement.

FIELD OF THE INVENTION

The present invention relates generally to land working implements, and more particularly to towable land levelers having tiltable land-working blades.

BACKGROUND

Applicant's prior PCT Application, published as WO/2016/109882, disclosed a towed land leveler implement whose frame was supported for rolling movement over the ground via a pair of split-beam walking beam assemblies on opposing sides of the frame. Front and rear beams of each split-beam walking beam assembly are pivotal relative to one another by an actuator, whereby changing the angle between the front and rear beams lifts or lowers the main pivot of the walking beam in order to adjust the height of the respective side of the vehicle frame. Through independent operation of the two walking beam actuators, the two walking beams can be used to adjust the tilt angle of a ground-working blade carried on the frame.

Disclosed herein is a novel improvement to this or other land levelers likewise having a tiltable ground working blade.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a towable implement comprising:

a frame supported for traveling movement over underlying ground;

a pull tongue connected to the frame and spanning forwardly thereof in a longitudinal direction of the implement for selective coupling to a tow vehicle for puling of said frame forwardly over said underlying ground;

a working blade carried on the frame in an orientation lying transversely of the longitudinal direction, said blade being operable in a working state in which a portion of a lower working edge of said working blade is engaged with said underlying ground to perform a working operation thereon;

wherein:

-   -   said working blade is selectively tiltable about a roll axis         that extends in the longitudinal direction to enable selecting         raising and lowering of opposing ends of the blade relative to         one another, thereby adjusting an angular position of the blade         about said roll axis to vary an orientation thereof relative to         the underlying ground to enable performance of different working         operations thereon; and     -   said working blade has a series of rigid fins distributed         discretely along a width of the blade in a direction transverse         to the longitudinal direction, and each rigid fin protrudes         downwardly beyond a reference working plane occupied by the         lower working edge of the blade, whereby in the working state of         said working blade, at least one of said rigid fins engages said         underlying ground in penetrating fashion to perform a         rudder-like action helping maintain a straight travel direction         of the implement.

BRIEF DESCRIPTION OF THE DRAWINGS

One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

FIG. 1 is an overhead plan view of a land leveler of the present invention, whose novel blade assembly is equipped with a series of rigid rudder-like fins attached to the underside thereof in spaced relation thereacross.

FIG. 2 is left side elevational view of the land leveler of FIG. 1.

FIG. 3 is a front elevational view of the land leveler of FIG. 1.

FIG. 4 is a rear elevational view of the land leveler of FIG. 1.

FIG. 5 is a front side perspective view of the land leveler of FIG. 1.

FIG. 6 is a bottom rear perspective view of the land leveler of FIG. 1.

FIG. 7 is a partial cross-sectional view of the land leveler of FIG. 1 as viewed along line A-A thereof.

FIG. 8 is an isolated view of a bottom plate of the blade of the land leveler, illustrating assembly of an individual fin and cooperating backstop member to the bottom plate of the blade.

FIG. 9 is an exploded view of the bottom plate, fin and backstop member of FIG. 8.

FIG. 10 is a rear elevational view of the land leveler with its blade in a tilted position where one side of the blade penetrates to a greater working depth in the ground than an opposing side of the blade, and the ground-penetrating fins help keep the implement on a straight travel path.

FIG. 11 is a rear elevational view of the land leveler on a hillside or other sloped land area, where the ground-penetrating fins again help keep the implement on a straight travel path.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

FIGS. 1 through 6 illustrate a towed land leveler implement 10 of the present invention. Like the land leveler disclosed in Applicant's aforementioned prior PCT application, the implement 10 features a pull tongue 12 equipped with a hitch connector 14 at a fore end of the tongue for coupling to the hitch of a tow vehicle for pulling of the implement along the ground in forward working direction F. A box blade assembly 16 is rigidly attached to the tongue and features a rear blade 18 spanning transversely of the tongue 12 in a position therebeneath adjacent an aft end thereof that lies opposite to the fore end at which the hitch connector 14 is mounted.

The novel box blade assembly of the present invention differs from Applicant's aforementioned prior PCT application in the inclusion of a series of rigid, rudder-like fins 100 attached to an underside of the box blade at discretely spaced intervals thereacross, whereby this novel bottom-finned blade arrangement is operable to help maintain straight travel of the implement 10 even when used in a tilted-blade condition where only a partial fraction of the blade width engages the underlying land, or where different parts of the blade width engage the underlying land to different depths. In such scenarios, the degree of resistance to forward travel of the blade is different at the differently submerged portions of the blade width, and this uneven loading of the blade across its width causes an unintended steering effect tending to swing the implement of a straight-travel position properly aligned behind the towing vehicle. Engagement of at least some of the fins with the earth provides a rudder-like effect resisting such unintended steering of the implement out its desired straight-travel position properly inline with the towing vehicle. The fins are also useful to help maintain the proper straight-travel position of the implement in other situations where conditions exist that would tend to deviate the implement from this position, for example during travel of the implement across a hillside or other sloped terrain, where gravity imparts a steering influence away from the proper straight-travel position.

More detail concerning this novel bottom-finned configuration of the blade is provided further below with reference to FIGS. 7 to 9, but first a general description of the land leveler itself if provided for context. Though the illustrated example of the land leveler is of a construction substantially similar to that disclosed in Applicant's aforementioned prior PCT application, where control over the tilt angle of the blade is effected by differential operation of two split-beam walking beam assemblies on opposing sides of the implement frame on which the blade is carried, it will be appreciated that the novel inclusion of a bottom-finned blade may be incorporated in any variety of land leveler implement with a tiltable ground-working blade.

When the implement is on horizontal ground and situated in a level-blade configuration holding the box blade parallel to the underlying ground, the pull tongue 12 lies in a vertically oriented central longitudinal plane of the implement. The rear blade 18 spans from one side of the central longitudinal plane to the other in an orientation perpendicular thereto, thus placing each lateral end of the rear blade 18 at an outboard location horizontally outward from the tongue 12. At each end of the blade 18, a respective planar end wall 20 projects forwardly therefrom in a plane parallel to the tongue 12. Box blade structures of this type are known in conventional land leveler designs, and thus are not described herein in further detail. As is also well known in the art, the tongue 12 extends forwardly from the box blade assembly 16 to the hitch connector 14 at the fore end of the tongue, which therefore defines the forward or leading end of the overall machine by which it is pulled by a tractor or other suitable tow vehicle.

With reference to FIG. 1, a frame assembly 22 resides behind the blade 18 and trails same during pulling of the implement by a tow vehicle. The frame 22 features a main cross-member 24 lying parallel to the blade 18 and perpendicularly transverse to the tongue 12. The cross-member 24 spans across the central longitudinal plane of the machine to place each of the cross-member 24 at an outboard location spaced laterally outward from the central longitudinal plane, just like the blade 18. The length of the cross-member between these two ends is parallel to, but shorter than, the length of the blade 18, whereby each end of the cross-member 24 lies inboard of the respective end wall 20 of the box blade assembly 16. A respective longitudinal frame member 26 is attached to the main cross-beam at each end thereof, lies perpendicular to the cross-member 24, and extends both forwardly and rearwardly therefrom. As best seen in the plan view of FIG. 1, the relative positioning of the cross-member 24 and each longitudinal member 26 fixed thereto may be reinforced by a respective gusset plate 27.

The forward end of each longitudinal frame member 26 features a pivotal connection 28 to the blade 18, which enables pivoting of the frame assembly 22 relative to the box blade assembly 16 about a pivot axis that lies perpendicularly transverse to the tongue and parallel to the blade 18 and the main cross-member 24. The pivotal connections 28 of the two longitudinal frame members 26 to the blade 18 share this same pivot axis, which due to its orientation, may be considered to be a pitch axis P of the implement 10. As best shown in FIG. 6, each of these pivotal connections 28 may be formed by pinning of the respective longitudinal frame member 26 to a respective pair of rearwardly extending lugs 30 on the rear face of the blade 18. A central lug 32 is fixed on the main cross-beam 24 and projects upwardly or rearwardly therefrom at a midpoint therealong, and one end of a hydraulic cylinder actuator 34 is pivotally coupled to the lug 32 by a pivot pin whose pivot axis is parallel to the pitch axis P. The opposing end of the hydraulic cylinder actuator 34 is likewise pivotally pinned to a pair of mounting brackets 36 on the rear of the blade 18. Extension and retraction of the actuator 34 thus pivots box blade assembly 16 and attached tongue 12 relative to the frame 12 about the pitch axis P, for example in order to lower the blade 18 down into engagement with the ground to perform a ground-working, earth-moving operation, or to raise the blade out of contact with the ground for transport of the machine.

Each longitudinal frame member 26 defines a respective side of the frame 22 on a respective one of the two opposing sides of the central longitudinal plane of the machine. Near the rearward end of each longitudinal frame member 26 that lies distally of the cross-member 24, a pivot pin or stub shaft 38 passes transversely through the longitudinal frame member 26 in a direction parallel to the pitch axis P, and projects outwardly from the longitudinal frame member 26 through front and rear beams 40, 42 of a respective split walking beam assembly 44 in order to pivotally connect same to the frame 22. Like a conventional walking beam, this split walking beam assembly 44 rotatably supports a pair of wheel axles 46, 48 near its opposing ends, so that two wheels 50, 52 mounted on these axles are rotatably carried on the walking beam in tandem positions relative to one another. The wheel axles 46, 48 lie parallel to the pivot pin or stub shaft 38. However, instead of the front wheel 50 and rear wheel 52 being rotatably supported on the same rigid beam, the front wheel 50 is rotatably carried on the front beam 40 that spans a front half of the overall walking beam assembly 44, and the rear wheel 52 is rotatably carried on a rear beam 42 that spans a rear half of the overall walking beam assembly 44. In the fore-aft longitudinal direction of the implement, the front end of the front beam is spaced forwardly of the forward end of the rear beam in the long, the rearward end of the rear beam is spaced rearwardly of the rear end of the front beam, and the front and rear beam overlap one another at the forward end of the rear beam and rear end of the front beam.

In each split walking beam assembly 44, the front and rear beams 40, 42 lie side-by-side with one another a short distance to the outside of the respective longitudinal frame member 26, and each feature a respective upright lug 58, 60 projecting upward from the topside of the beam 40, 42. A respective hydraulic cylinder actuator 62 of each walking beam assembly 44 has its opposing ends pivotally coupled to the front and rear top lugs 58, 60 by pivot pins whose axes lie parallel to the pitch axis P of the machine.

The stub shaft or pivot pin 38 passing through the respective longitudinal frame member 26 also passes through both the front and rear beams 40, 42 of the respective walking beam assembly 44 at an area where the two beams 40, 42 overlap in the longitudinal direction of the machine. The stub shaft or pivot pin 38 thus defines a main walking beam pivot axis W on which the collective walking beam assembly is pivotal relative to the frame 22, and also defines a coincident second walking beam pivot axis about which the front and rear beams 40, 42 are pivotable relative to one another by extension and retraction of the walking beam actuator 62. This direct coupling together of the front and rear wheel carrying beams of the walking beam assembly by the same shaft or pin that couples the walking beam assembly to the frame 22 reduces the number of parts by avoiding an intermediary between the front and rear beams on which the front and rear wheels are mounted and sharing the same pivot point for both the relative pivoting between the front and rear beams and the pivoting of the overall walking beam assembly relative to the frame.

When the length of the walking beam actuator 62 is maintained, an angle α measured between the front and rear beams 40, 42 about the axis of the stub shaft or pivot pin 38 walking beam assembly 44 is likewise maintained, and the walking beam assembly acts as a conventional walking beam in which the positions of the two wheels 50, 52 are stationary relative to one another. On the other hand, each side of the frame 22 can be raised and lowered relative to the ground G by varying the angle α between the front and rear beams 40, 42 through extension and retraction of the respective walking beam actuator 62. Particularly, if angle α is measured between the undersides of the two beams 40, 42, then extending the length of the actuator 62 pushes apart the front and rear lugs 58, 60 at the topsides of the beams 40, 42, thus forcing the undersides of the two beams toward one another and reducing the angle α. This pushes each of the two wheels 50, 52 downwardly against the ground G on an arcuate path about the stub shaft or pivot pin 38, thereby lifting the respective side of the frame 22 upwardly away from the ground G. Conversely, retracting the length of the actuator 62 draws the front and rear lugs 58, 60 toward one another, thus drawing the undersides of the two beams away from one another and increasing the angle α in order to lower the respective side of the frame 22 downwardly toward the ground G. By using the actuator 62 of each walking beam assembly to vary the positions of the two respective wheels 50, 52 relative to one another about the respective stub shaft or pivot pin 38, the height of each side of the frame can thus be varied, and the heights at the opposing sides of the frame can be set to different values in order to tilt the frame 22 and the connected box blade assembly 16 about a longitudinal roll axis R that lies perpendicular to the pivot axes W of the walking beam assemblies 44.

In the illustrated embodiment, the front beam 40 of each split walking beam assembly 44 resides adjacent the outer side of the respective longitudinal frame member 26, and the rear beam 42 resides opposite the longitudinal frame member 26 to the outside of the front beam 40. The rear wheel 52 is mounted to the inside of the rear beam 42, thus riding on the ground in a position trailing behind the longitudinal frame member 26 in the shadow of same. The front wheel 50 is mounted to the outside of the front beam 40, i.e. on the side thereof opposite the frame 22. The front wheel 50 resides nearer to the plane of the respective end wall 20 of the box blade assembly 16 than the rear wheel, but still a short distance inboard from this plane. By placing the two wheels of each walking beam assembly on opposite sides thereof, the wheels are slightly spaced apart from one another in the transverse direction of the machine. This way, a rock, bump or other surface disruption on the ground that is met by one wheel will not necessarily be hit by the other.

FIGS. 1 through 4 show the blade in a level orientation parallel to the ground G, i.e. in a horizontal orientation when all four wheels are resting on a planar, horizontal ground surface. As shown in FIG. 2, the value of angle α is the same for the two walking beam assemblies when the blade is level, specifically at a value of 180-degrees in the case of the illustrated scenario. In comparison, FIG. 10 shows the box blade and frame in a tilted orientation with the left side thereof in a lower position than the right side. From the initially level blade and frame orientation of FIGS. 1 through 4, this tilted orientation was achieved by collapsing the actuator 62 of the left walking beam assembly in order to increase the angle α thereof, and extending the actuator of the right walking beam assembly in order to decrease the angle α thereof.

The implement may be equipped with a control system for monitoring and automatically controlling the tilt angle of the frame and blade about the roll axis R, and this may be of the type described in Applicant's aforementioned PCT application, the entirety of which is incorporated herein by reference. Although some embodiments of the present invention may employ the automated control of the blade angle, other embodiments may be manually controlled by the operator of the tow vehicle, for example by conveying electrical control signals from a manual lever or other control mechanism in the operator cabin of the tow vehicle to the directional control valve, for example via suitable wiring run along the pull tongue 12 of the implement, or by way of a wireless communication link.

While the illustrated embodiment features two split walking beam assemblies 44, another embodiment may feature one conventional fixed-beam walking assembly, whereby the tilt angle of the blade is set by adjusting the one split walking beam assembly to set the height at one side of the frame, without changing the height of the other side of the frame. While some embodiments with two split walking beam assemblies may employ hydraulic control system that automatically operates the two walking beam actuators in inverse of one another, other embodiments are also contemplated. For example, split walking beam assemblies on opposing sides of a vehicle or implement (whether a land leveler, or other machine) may be beneficial even with other control configurations, for example in a control configuration where the two walking beam actuators are again operated simultaneously, but in the same direction, so as to control and overall height of the vehicle, or in a control configuration in which the two walking beam actuators are operable independently of one another, for example to set a desired height at one side of the frame, and a desired tilt angle of the frame.

The inclusion of the rigid fins 100 along the bottom of the blade 18 can be seen in FIGS. 3 to 6. The fins 100 are discretely, and preferably uniformly, spaced from one another across the width of the blade, i.e. in a transverse direction of the implement that is perpendicular of the longitudinal direction of the roll axis R about which the blade is adjustable tiltable. As shown, the rigid fins 100 are preferably arrayed over a substantial majority of the blade's overall width, preferably spanning at least a central two-thirds of the blade width. In the illustrated example, the array of fins span from just outside of one of the two walking beam assemblies to just outside the other. As best seen in FIGS. 8 and 9, each fin in the illustrated example has a planar main body 102 residing in a plane that lies longitudinally of the implement, and that is vertically oriented when the implement is on horizontal ground in the level-blade configuration. Each end fin also includes a planar mounting flange 104 projecting laterally from one side of the main body 102 at a right angle thereto, therefore lying in a perpendicular plane that is of horizontal orientation when the implement is on horizontal ground in the level-blade configuration. The illustrated mounting flange 104 has two fastener holes 106 through which the rigid fin 100 is fastened into its installed position attached to the box blade assembly 16.

The main body 102 and mounting flange 104 of each rigid fin 100 are preferably seamlessly integral parts of unitary metal body having a right angle between these two integral parts. The shape of the illustrate fin is further characterized a concavely contoured leading edge 108A, terminating at a relatively sharp point or tip 110A at its bottom end, where the leading edge 108 intersects with a bottom edge 112 of the fin. In the illustrated example, the fin has a symmetric shape, thus having a matching concavely curved trailing edge 108B also terminating in a relatively sharp point or tip 110B. Each fin is thus reversable, whereby once the leading edge has been subjected to notable wear from repeated use, the fin can be removed, and flipped into a reverse orientation placing the formerly rearward facing trailing edge 108B into a forwardly facing position, and likewise placing the formerly forward facing leading edge 108A into a rearwardly facing position. The pointed configuration of these edges at their distalmost terminus helps reduce resistance of the fin to movement through the earth.

Referring to FIG. 7, the blade 18 has a curved blade wall 114 with a concave front side 114A for moving earth forwardly during towed use of the implement to perform an earth working operation (levelling, grading, ditching, etc.), or clearing away other material from atop the earth in an earth clearing operation; and an opposing convex rear side 114A. The front side 114A of the curved blade wall 114 has attached thereto, and a bottom end thereof, a a hardened wear strip 116 that defines the lowermost and forwardmost working edge 116A of the blade that engages with the ground during ground working or ground clear operations. The working edge 116A resides in a plane that is perpendicular to the central longitudinal plane of the implement, and thus lies horizontally when the implement is on horizontal ground in the level-blade configuration. This plane of the working edge 116A is also referred to herein as the working plane, for brevity. The curved blade wall 114 curves upwardly away from this hardened wear strip 116.

A mounting structure 118 of the blade is attached to and spans between the two end walls 20 of the box blade assembly 16 at a location behind the curved blade wall 114 and beneath the convex rear side 114B thereof for the purpose of mounting the rigid fins 100 to the box blade assembly 16. The mounting structure has a bottom wall 120 whose front edge meets the rear side 114B of the curved blade wall 114 at the terminal lower end thereof just behind the wears strip 116, whereby this bottom wall 120 of the mounting structure resides in a plane parallel to the working plane at a slight elevation thereabove. In the illustrated example, the mounting structure has an L-shaped cross-sectional shape when cross-sectioned parallel to the central longitudinal plane of the implement, and thus is characterised by an upright rear wall 122 standing upright from the bottom wall 120 of the mounting structure at rear end thereof. The bottom wall and rear wall of the mounting structure cooperatively form a channel like space running along the rear side of the curved blade wall. At spaced intervals along this channel space are a series of blade-reinforcing gussets 124 that brace against all three of the rear side 114B of the curved blade wall 114, the bottom wall 120 of the mounting structure, and the rear wall 122 of the mounting structure.

The underside of the mounting structure's bottom wall 120 denotes a mounting surface against which the mounting flange 104 of each rigid fin 100 abuts in flush relation thereto. Since the mounting structure's bottom wall 120 is slightly elevated above the working plane of the blade, the mounting flange 104 of each rigid 100 likewise resides in slightly elevated relation above the working plane, or at least no lower than said working plane. Accordingly, only the main body 102 of each rigid fin reaches downwardly beyond the working plane of the blade's working edge 116A, whereby the integrity of the fins attachment to the mounting structure 118 is not subject to direct wear exposure during use of the implement. With reference to FIGS. 8 and 9, each rigid fin of the illustrated embodiment 100 is accompanied by a respective backstop member 126 that is affixed to the bottom wall to protrude from the underside thereof at a position immediately behind the mounting flange 104 of the rigid fin 100. The backstop member 126 can be installed prior to the respective fin 100, and then used to help properly align the respective fin 100 during installation thereof. Additionally, in use of the implement, where forward cutting of the fin's leading edge 108A through the earth imparts a rearward loading force on the fin, the inclusion of the backstop member means that at least some of this loading force is exerted against the backstop member 126, and not the bolts, rivets or other fasteners (not shown) by which the mounting flange 104 of the fin is attached to the mounting structure's bottom wall, thus helping provide a robust degree of mounting integrity for each fin 100.

Still referring to FIGS. 8 and 9, the mounting structure's bottom wall is manufactured with predefined mounting points thereon for receiving subsequent installation of the rigid fins and respective backstop members in predetermined positions at the appropriate working orientation described above. For each fin, a respective set of predefined mounting point comprise three pre-cut, pre-drilled or pre-punched holes in the mounting structure's bottom wall 120: two fin-mounting holes 128, 130 discretely spaced in the longitudinal direction of the implement to match the two fastener holes 106 in the mounting flange 104 of the fin 100, and a singular stop-mounting hole 132 residing at a longitudinally spaced location behind the two fin-mounting holes 128 to receive an upper portion of the respective backstop member 126. In the illustrated embodiment, each backstop member 126 has an inverted T-shape, with an upper mounting tab 126A of rectangular cross-section matching a rectangular shape of the stop-mounting hole 132, and a lower cross-bar 126B lying perpendicularly cross-wise of the upper mounting tab at the bottom end thereof in an orientation perpendicular to the central longitudinal plane of the implement so as to received abutted contact of the rear end of the fin's mounting flange 104. The upper mounting tab 126A is inserted upwardly into the stop-mounting hole 132 of the mounting structure's bottom wall 120, and affixed thereto, for example by welded attachment. The respective fin 100 is then fastened to the mounting structure's bottom wall 120 via the aligned fastener holes 106 and fin-mounting holes 130, with the rear end of the fin's mounting flange 104 situated immediately adjacent the cross-bar 126B of the backstop member 126 in abutting contact therewith.

FIG. 10 illustrates one example of a ground working operation where the fins 100 are beneficial to help maintain a straight travel direction of the towed implement. Here, the left side of the blade 18 is has been set to a lower height than the right side to achieve a tilted blade configuration where the left side of the blade penetrates deeper into the ground G than in the right side. In the illustrated example, the right side of the blade doesn't penetrate the ground at all, though this need not necessary be the case. The areas of the blade penetrating the ground to greater depths are pushing a greater volume of earth than less submerged areas of the blade, creating an imbalanced load where the left side of the blade is facing significant resistance to forward travel, while the elevated or less-submerged right side of the blade is experiencing zero or lesser load and travel resistance. Thus unbalanced loading imparts a leftward steering effect, as the less-loaded right side of the blade has a tendency to advance relative to the more heavily loaded right side. However, the fins 100, or least a partial subset of the fins 100, are engaged into the earth, and due to their longitudinally oriented positions, act as small rudders helping resist the leftward steering effect and better maintain a proper straight-ahead travel direction of the implement, keeping it properly inline with the towing vehicle. The fins serve the same travel-straightening purpose to counteract a rightward steering effect in scenarios where the rightward side of the blade is more submerged in the ground than the left side. It will be appreciated that the travel-straightening effect of the fins would be operable regardless of whether the land leveler is of the illustrated type, where the frame of the implement is tilted through differential raising/lowering of ground wheels relative to the frame on opposing sides of the frame in order to tilt the frame-carried blade through this tilting of the frame itself, or whether the land leveler is of a different type where the blade is instead tilted relative to the frame through suitable blade-tilting actuators acting between the frame and the blade.

FIG. 11 shows another example where the fins are useful to help maintain a straight travel direction of the implement. Here, the implement is travelling across a hillside or other notably sloped area of land, where the ground G is thus at notable incline in the transverse direction lying cross-wise of the implement's forward longitudinal travel. Whether the blade is tilted (as shown in FIG. 10) relative to the ground to change the ground's surface profile (e.g. in a leveling, grading or ditching operation), or is in an level or untiltled condition parallel to the ground to leave the ground profile the same (e.g. in a scraping operation reducing the ground elevation, or a clearing operation clearing snow or other accumulated material from the ground), engagement of the full set of fins (in a level-blade scenario) or at least a subset thereof in a tilted blade scenario will help counteract a gravity-induced steering effect tending to pull the implement downwardly of the inclined ground G as the implement travels thereacross.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the scope of the claims without departure from such scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense. 

Amended claims:
 1. A towable implement comprising: a frame supported for traveling movement over underlying ground; a pull tongue connected to the frame and spanning forwardly thereof in a longitudinal direction of the implement for selective coupling to a tow vehicle for puling of said frame forwardly over said underlying ground; a working blade carried on the frame in an orientation lying transversely of the longitudinal direction, said blade being operable in a working state in which a portion of a lower working edge of said working blade is engaged with said underlying ground to perform a working operation thereon; wherein: said working blade is selectively tiltable about a roll axis that extends in the longitudinal direction to enable selecting raising and lowering of opposing ends of the blade relative to one another, thereby adjusting an angular position of the blade about said roll axis to vary an orientation thereof relative to the underlying ground to enable performance of different working operations thereon; and said working blade has a series of rigid fins distributed discretely along a width of the blade in a direction transverse to the longitudinal direction, and each rigid fin protrudes downwardly beyond a reference working plane occupied by the lower working edge of the blade, whereby in the working state of said working blade, at least one of said rigid fins engages said underlying ground in penetrating fashion to perform a rudder-like action helping maintain a straight travel direction of the implement.
 2. The towable implement of claim 1 wherein the working blade comprises a curved blade wall curving upwardly away from the working edge of the working blade, and a mounting structure that resides in fixed relation to the curved blade wall at a position therebehind, and to which the rigid fins are mounted.
 3. The towable implement of claim 2 wherein the mounting structure resides at equal or slightly greater elevation than the lower working edge of the working blade.
 4. The towable implement of claim 2 wherein the mounting structure resides beneath the convex rear side of the curved blade wall.
 5. The towable mounting implement of claim 2 wherein a mounting structure to which the rigid fins are mounted comprises a mounting surface to which each rigid fin is attached, and one or more backstops protruding from said mounting surface, each in a position behind at least one of said rigid fins.
 6. The towable mounting implement of claim 5 wherein the lower mounting structure has predefined mounting points thereon at which the rigid fins and/or the one or more backstops are mounted.
 7. The towable mounting implement of claim 6 wherein the predefined mounting points comprise, for each fin, a predefined a pair of fin-mounting holes spaced apart in the longitudinal direction and through said fin is fastened in place.
 8. The towable mounting implement of claim 7 wherein the predefined mounting points, for each fin, further comprise a predefined backstop-mounting hole that resides behind said pair of fin-mounting holes and at which a respective backstop is mounted.
 9. The towable mounting implement of claim 8 wherein said predefined backstop opening receives therein an upper portion of said respective backstop.
 10. The towable mounting implement of claim 1 wherein each fin is a reversible.
 11. The towable mounting implement of claim 1 wherein each fin has symmetrically configured leading and trailing edges.
 12. The towable mounting implement of claim 1 wherein each fin tapers to a point at a leading edge thereof.
 13. The towable mounting implement of claim 1 wherein each fin has a concave leading edge. 